I cannot recall any time in my life when I cared that teleportation used the astral plane or that ghosts "needed" the ethereal plane. I've run plenty of games where teleportation just meant "You go poof!" and ghosts may have had the "Ethereal" quality, but all that meant was a set of specific game effects, no need to drag in the planes. As for infinite planes... meh. My cosmologies tend to have finite planes, but infinite planes don't bother me -- if you figure there's infinite material worlds, then, you need an infinite number of devils to plot against them, and an infinite number of angels to stop them. I always felt each "part" of an infinite plane was "close to" a given game world, so that if you were on World A, you'd go to the hell/abyss/heaven region which was for "your world", and you'd have little reason or motive to wander far enough to find someone else's "part" of the plane -- but you could if you really wanted to, I guess.
Overall, yeah, more meaningless change for change's sake, pretty typical of 4e design and trivially ignored by player's and DMs. As is likewise typical, the design focus is on conformity and "how we think you should play", not on "Here's some great tools! Build what you want with them!", which was the 3e model -- but I guess they've found that people buy a lot more of the "Build a TIE Fighter" lego kits than the "Here's 500 pieces, build what you want" kits, and did their game design accordingly. Can't blame them for Giving The People What They Want -- I just blame the people.
Me, I will do what I always do -- roll my own cosmology and deal with any trivial rules issue when they come up. I do not need a "plane of shadow" to have a creature with the "shadow" type. It's kind of amusing -- they're getting away from one of the key design conceits of 4e, which is that there's a total disconnect between the game rules and the game world. "Shadow" doesn't need to mean a thing, and really doesn't -- a creature with the "Shadow" keyword can manipulate/affect assorted numbers in assorted ways, and that's ALL it means. Two "shadow" creatures might actually be totally different in origin and backstory, they just have a common set of mechanical tricks, and are affected by any power which targets "shadow", however defined.
(Pretty much every campaign I've run in the past 20-odd years has been part of the same sprawling meta-universe anyway, whether I have been using GURPS, Hero, D&D, or SOTC, and whether it was fantasy, pulp, superheroes, sci-fi, or modern horror. My cosmology is highly fractal, with complex levels of meta-reality. The entire Great Wheel is just a local phenomenon of a small cluster of realities... )